The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a functional block diagram of an exemplary motor driver 100 according to the prior art is presented. The motor driver 100 includes a power supply 102, such as a 12 Volt (V) power supply, and a linear regulator 104, such as a 5 Volt (5V) linear regulator. The power supply 102 receives an input signal, VIN, such as a 12V signal. The power supply 102 provides an output signal, VPWR, at approximately 12V to the linear regulator 104, other circuitry 106 that may operate at 12V, and output power transistors 108.
The power supply 102 may include a voltage reference 118, such as a bandgap reference circuit or a reference circuit based upon diode voltage drops, to create an accurate output, for example at 12V. In various implementations, the input signal, VIN, and the output signal, VPWR, are smaller or larger than 12V. The linear regulator 104 produces a stable power signal, VDD5_REG, which may be at approximately 5V.
The linear regulator 104 communicates with a capacitor 110, which may be external to the motor driver 100. The capacitor 110 provides loop stability and ripple filtration for the linear regulator 104. The VDD5_REG signal is received by the output power transistors 108 and by other circuitry 112 that may operate at 5V. The output power transistors 108 control current through a motor 114, which may be external to the motor driver 100. The linear regulator 104 may include a bandgap reference 116 to provide a reasonably accurate voltage that is temperature independent.